Theoretical results are presented which show that noiseless phase quadrature amplification is possible, and limited experimentally only by the efficiency of the phase detection system. Experimental results obtained using a Nd:YAG laser show a signal gain of 10dB and a signal transfer ratio of T_s=0.9. This result easily exceeds the standard quantum limit for signal transfer. The results also explicitly demonstrate the phase sensitive nature of the amplification process.
@article{arxiv.quant-ph/9811015,
title = {Noiseless phase quadrature amplification via electro-optic feed-forward},
author = {Ben C. Buchler and Elanor H. Huntington and Timothy C. Ralph},
journal= {arXiv preprint arXiv:quant-ph/9811015},
year = {2009}
}